The Utah Territory was an organized territory of the United States from 1850 to 1896. It was formed on September 9, 1850 from the northeastern part of the territory ceded by Mexico to the United States in the Treaty of Guadalupe Hidalgo 1848 . On the same day, the western state of California was admitted to the Union and the southern New Mexico Territory was formed. This was preceded by the compromise of 1850 .
In 1849, Mormon settlers in the Salt Lake Valley petitioned Congress unsuccessfully for the admission of the provisional state of Deseret with its capital in Salt Lake City to the Union. In the Utah War of 1857/58 the Mormon state was smashed.
In 1861, the new Nevada Territory was formed from the western part of the area and parts of the east were ceded to the Colorado Territory and the Nebraska Territory . In 1868 additional areas went to the state of Nevada and the Wyoming Territory (see maps).
The ongoing clashes with the Mormons were one reason for the long period between the formation of the territory and its union as the state of Utah (45th state) on January 4, 1896.